Regeneration of a coke-deactivated catalyst comprising a combination of platinum germanium and halogen with a porous carrier material

ABSTRACT

A DEACTIVATED HYDROCARBVON CONVERSION CATALYST, WHICH IS A COMBINATION OF A PLATINUM GROUP COMPONENT, A GERMANIUM COMPONENT AND A HALOGEN COMPONENT WITH A POROUS CARRIER MATERIAL AND WHICH HAS BEEN DEACTIVATED BY A DEPOSITION OF CARBONACEOUS MATERIAL THEREON DURING A PREVIOUS CONTACTING WITH A HYDROCARBON CHARGE STOCK AT HYDROCARBON CONVERSION CONDITIONS, IS REGNERATED BY THE SEQUENTIAL STEPS OF: (1) BURNING CARBON FROM THE DEACTIVATED CATALYST AT A RELATIVELY LOW TEMPERATURE WITH A SUBSTANTIALLY SULFUR-FREE FIRST GASEOUS MIXTURE CONTAINING RELATIVELY SMALL AMOUNTS OF OXYGEN, H2O AND HC1; (2) TREATING THE RESULTING CATALYST AT A RELATIVELY HIGH TEMPERATURE WITH A SECOND GASEOUS MIXTURE CONTAINING O2, H2O AND HC1; (3) PURGING OXYGEN FROM CONTACT WITH THE RESULTING CATLYST; AND (4) REDUCING THE RESULTING CATALYST BY CONTACTING WITH A SUBSTANTIALLY SULFUR-FREE THIRD GASEOUS MIXTURE CONTAINING HYDROGEN AND SAMLL AMOUNTS OF H2O AND HC1. KEY FEATURES OF THE REGENERATION METHOD INVOLVE THE PRESENCE OF BOTH H2O AND HC1 IN THE GAGEOUS MIXTURES USED IN THE CARBON-BURNING, OXYGEN-TREATING AND REDUCTION STEPS, THE USE OF SULFUR-FREE GASEOUS MIXTURES IN ALL OF THESE STEPS, AND THE CAREFUL CONTROL OF THE MOLE RATIO OF H2O TO HC1 EMPLOYED IN EACH OF THESE GASEOUS MIXTURES.

United States Patent Office 3,654,182 Patented Apr. 4, 1972 US. Cl. 252415 -15 Claims ABSTRACT OF THE DISCLOSURE A deactivated hydrocarbon conversion catalyst, which is a combination of a platinum group component, a germanium component and a halogen component with a porous carrier material and which has been deactivated by a deposition of carbonaceous material thereon during a previous contacting with a hydrocarbon charge stock at hydrocarbon conversion conditions, is regenerated by the sequential steps of: (l) burning carbon from the deactivated catalyst at a relatively low temperature with a substantially sulfur-free first gaseous mixture containing relatively small amounts of oxygen, H and HCl; (2) treating the resulting catalyst at a relatively high temperature with a second gaseous mixture containing 0 H 0 and HCl; (3) purging oxygen from contact with the resulting catalyst; and (4) reducing the resulting catalyst by contacting with a substantially sulfur-free third gaseous mixture containing hydrogen and small amounts of H 0 and HCl. Key features of the regeneration method involve the presence of both H 0 and HCl in the gaseous mixtures used in the carbon-burning, oxygen-treating and reduction steps, the use of sulfur-free gaseous mixtures in all of these steps, and the careful control of the mole ratio of H 0 to HCl employed in each of these gaseous mixtures.

The subject of the present invention is a method for regenerating a coke-deactivated hydrocarbon conversion catalyst comprising a combination of a platinum group component, a germanium component and a halogen component with a porous carrier material. Typically, the catalyst has been deactivated by the deposition of carbonaceous materials thereon during a previous contacting with a hydrocarbon charge stock at an elevated temperature. In essence, the present invention provides a specific sequence of carbon-burning and catalyst-treatment steps which are all conducted with a sulfur-free gas stream containing H 0 and HCl and which are specifically designed to result in a regenerated catalyst possessing activity, selectivity, and stability characteristics which are equivalent to those observed with a fresh, undeactivated catalyst.

Composites having a hydrogenation-dehydrogenation function and a cracking function are Widely used today as catalysts in many industries, such as the petroleum and petrochemical industry, to accelerate a wide spectrum of hydrocarbon conversion reactions. Generally, the cracking function is thought to be associated with an acidacting material of the porous, adsorptive, refractory oxide type which is typically utilized as the support or carrier for a heavy metal component such as one or more of the metals or compounds of metals of Group IV through VIII of the Periodic Table to which are generally attributed the hydrogenation-dehydrogenation function.

These catalytic composites are used to accelerate a wide variety of hydrocarbon conversion reactions such as hydrocracking, isomerization, dehydrogenation, hydrogenation, hydrogenation, desulfurization, cylization, alkylation, polymerization, cracking, hydroisomerization, etc. In many cases, the commercial applications of these catalysts are in processes where more than one of these reactions are proceeding simultaneously. An example of this latter type of process is reforming wherein a hydrocarbon feed stream containing paraflins and naphthenes is subjected to conditions which promote dehydrogenation of naphthenes to aromatics, isomerization of parafiins and naphthenes, hydrocracking of naphthenes and paratfins and the like reactions, to produce an octane-rich and aromatic-rich product stream. Another example is a hydrocracking process wherein catalysts of this type are utilized to effect selective hydrogenation and cracking of high molecular weight unsaturated materials, selective hydrocracking of high molecular weight materials, and other like reactions, to produce a generally lower boiling, more valuable output stream. Yet another example is an isomerization process wherein a hydrocarbon fraction which is relatively rich in straight-chain parafiin components is contacted with a dual-function catalyst to produce an output stream rich in isoparaflin compounds.

Regardless of the reaction involved or the particular process involved, it is of critical importance that the dualfunction catalyst exhibit not only the capability to initially perform the specified functions, but also that it has the capability to perform them satisfactorily for prolonged periods of time. The analytical terms used in the art to measure how well a particular catalyst performs its intended functions in a particular hydrocarbon reaction environment are activity, selectivity, and stability. And for purposes of discussion here, these terms are conveniently defined for a given charge stock as follows: (1) activity is a measure of the catalysts ability to convert hydrocarbon reactants into products at a specified severity level where severity level means the conditions usedthat is, the temperature, pressure, contact time and presence of diluents such as H 2) selectivity refers to the amount of desired product or products obtained relative to the amount of reactants converted; (3) stability refers to the rate of change with time of the activity and selectivity parametersobviously the smaller rate implying the more stable catalyst. In a reforming process, for example, activity commonly refers to the amount of conversion that takes place for a given charge stock at a specified severity level and is typically measured by octane number of 0 product stream; selectivity refers to the amount of CH- yield that is obtained at the particular severity level; and stability is typically equated to the rate of change with time of activity, as measured by octane number of C product and of selectivity as measured by C yield. Actually, the last statement is not strictly correct because generally a continuous reforming process is run to produce a constant octane C product with a severity level being continuously adjusted to attain this result; and, furthermore, the severity level is for this process usually varied by adjusting the conversion temperature in the reaction zone so that, in point of fact, the rate of change of activity finds responsein the rate of change of conversion temperature and changes in this last parameter are customarily taken as indicative of activity stability.

As is well known to those skilled in the art, the principal cause of observed deactivation or instability of these dualfunction catalysts, when they are used in a hydrocarbon conversion process, is associated with the formation of coke or carbonaceous materials on the surface of the catalyst during the course of the reaction. More specifically, the conditions utilized in these hydrocarbon conversion processes typically result in the formation of heavy, black, solid or semi-solid carbonaceous material which deposit on the surface of the catalyst and gradually reduce its activity by shielding its active sites from the reactants. Recently, I have disclosed a new dual-function catalytic composite which possesses improved activity, selectivity, and stability characteristics when it is employed in a process for the conversion of hydrocarbons of the type which has heretofore utilized dual-function catalytic composites such as processes for isomerization, dehydrogenation, hydrogenation, alkylation, transalkylation, dealkylation, cyclization, dehydrocyclization, cracking, hydrocracking, reforming, and the like processes. In particular, I have determined that the use of a catalyst comprising a combination of a platinum group component, a germanium component, and a halogen component with a porous carrier material can enable the performance of hydrocarbon conversion processes which traditionally have utilized dualfunction catalysts, to be substantially improved. For example, it has been demonstrated that the overall performance characteristics of a reforming process can be sharply improved by the use of this catalytic composite. Not unexpectedly, the deactivation of this catalyst occurs in much the same manner as for any other hydrocarbon conversion catalyst having a platinum metal component when it is employed in the hydrocarbon conversion service. Accordingly, the principal mode of deactivation of this catalyst is the deposition of coke, volatile hydrocarbons, and other carbonaceous material on the surface of the catalyst which eventually cover the catalytically active sites of the catalyst, thereby shielding them from the reactants or blocking access of the reactants to the sites. These deposits cause a gradual decline in activity and selectivity of the catalyst and a gradual loss of its capability to perform its intended function. Depending somewhat on the performance requirements imposed on the process utilizing the catalyst, at some point in time the catalyst becomes so clogged with carbonaceous materials that it either must be regenerated or discarded. Heretofore, substantial difficulty has been encountered in regenerating this platinum-germanium hydrocarbon conversion catalyst. More specifically, it has been ascertained that the application of conventional regeneration techniques, which have long been practiced in the art of regenerating dualfunction hydrocarbon conversion catalysts, has not been successful in restoring the initial activity, selectivity, and stability characteristics of this catalyst. Typicaly, attempts at regeneration of this catalyst by a conventional carbonburning procedure with an oxygencontaining gas have resulted in a regenerated catalyst having an extremely low activity for the conversion of hydrocarbons and containing a substantially reduced amount of halogen. Attempts at restoring the initial level of halogen contained in the catalyst by well known halogen-adjustment procedures on the regenerated catalyst have been uniformly unsuccessful. Likewise, when the deactivated catalyst also contains a sulfur component, this regeneration problem is greatly magnified and compounded. More specifically, when this recently developed catalyst has been exposed to contact with sulfur or sulfur-containing compounds, either, because of presulfiding, because of the presence of sulfur in the charge stock, or because of upsets in a treating process used on the charge stock therefor, the response of the resulting sulfur-containing catalyst to a conventional carbon-burning regeneration procedure is completely negative,-and the catalyst is thereby vpermanently deactivated. In other words, this catalyst is acutely sensitive to the procedure used to regenerate even when it does not contain sulfur, and when sulfur is present, the already difficult regeneration problem increases by an order of magnitude.

Based upon my recognition of the acute sensitivity of this catalyst to the presence of sulfur or sulfur oxides during the course of the regeneration procedure, I have now found that a particularly advantageous method of regeneration involves the substantially complete removal of labile sulfur from this catalyst prior to the burning of carbon therefrom coupled with careful control of the gas streams used in the various steps of the regeneration method to exclude therefrom sulfur and sulfur oxides. Moreover, I have discerned that it is particularly beneficial to conduct each of the major steps of the regeneration method with a gas stream containing both H 0 and HCl. More precisely, I have now found a specific sequence of steps which enables the successful regeneration of this recently discovered catalyst, and essential features of my method are: substantially complete removal of labile sulfur prior to burning of any carbon from the catalyst; careful control of the temperature of the catalyst throughout the regeneration steps; exclusion of sulfur and sulfur oxides from the gas streams used in all steps; presence of both H 0 and HCl in the gas streams used in the major steps thereof (i.e., the sulfur-stripping step, the carbonburning step, the oxygen treatment step, and the final reduction step).

It is, therefore, a principal object of the present invention to provide a method for regenerating a hydrocarbon conversion catalyst comprising a combination of a platinum group component, a germanium component and a halogen component, with a porous carrier material, which catalyst has been deactivated by contact with a hydrocarbon charge stook at elevated temperatures. A corollary object is to provide a solution to the problem of regenerating this catalyst when it contains labile sulfur, which solution enables the substantial restoration of the activity, selectivity, and stability characteristics of the original catalyst. An overall object is to extend the total catalyst life of these recently developed catalysts and to obtain more efficient and effective use of these catalysts during their active life.

In brief summary, one embodiment of the present invention involves a method for regenerating a deactivated hydrocarbon conversion catalyst comprising a combination of a platinum group component, a germanium component and a halogen component with a porous carrier material, the catalyst having been deactivated by the deposition of carbonaceous material thereon during a previous contacting with a hydrocarbon charge stock at hydrocarbon conversion conditions. Furthermore, the hydrocarbon conversion process in which the catalyst was deactivated, was conducted in a sulfur-free manner so that the deactivated catalyst is substantially free of labile sulfur. The first step of the regeneration method, in this embodiment, involves contacting the deactivated catalyst with a substantially sulfur-free first gaseous mixture containing O ,H O and HCl at a temperature of about 375 to about 450 C. for a period sufficient to substantially remove the carbonaceous material from the catalyst. In addition, this first gaseous mixture contains 0 in an amount of about 0.2 to about 3 mole percent and has a mole ratio of H 0 to HCl selected from the range of about 20.1 to about :1. In the next step, the catalyst resulting from the first step is treated with 0 by contacting it with a substantially sulfur-free second gaseous mixture containing 0 HCl and H 0 at a temperature of about 450 to about 550 C. for a period of about 0.5 to about 10 hours. Like the first gaseous mixture, the second mixture also has a mole ratio of H 0 to HCl of about 20:1 to about 100:1; in addition, it contains about 0.2 to about 25 mole percent 0 with an amount of about 1 to 5 mole percent being preferred. After this oxygen treatment step, oxygen is purged from contact with the resulting treated catalyst; and thereafter in the final step, the catalyst is contacted with a substantially sulfur-free third gaseous mixture comprising hydrogen, H and HCl at a temperature of about 300 to about 600 C. for a final period of about 0.5 to about hours, thereby pro ducing the regenerated catalyst. Like the first and second gaseous mixtures, this third mixture contains H 0 and HCl; however, in this step, the mole ratio of H 0 to HCl is selected from the range of about 20:1 to about 500:1.

In a second embodiment, the present invention is a method for regenerating a deactivated catalyst comprising a combination of a platinum group component, a germanium component, a halogen component and a sulfur component with a porous carrier material. The catalyst also contains a carbon component which was formed by deposition of carbonaceous material thereon during a previous contacting with a hydrocarbon charge stock at hydrocarbon conversion conditions. The first step of the instant method, in this embodiment, involves contacting the deactivated catalyst with a substantially sulfur-free hydrogen stream at a temperature of about 350 to about 600 C. for a period extending until the resulting efiluent gas stream is substantially free of hydrogen sulfide. This hydrogen stream preferably contains H 0 and HCl in amounts selected to result in a mole ratio of H 0 to HCl of about 20:1 to about 100: 1. After this first step, hydrogen is purged from contact with the catalyst, and it is subjected to contact with a substantially sulfur-free first gaseous mixture containing 0 H 0, and HCl at a temperature of about 375 to about 450 C. for a period of time sufficient to substantially remove the carbonaceous materials from the catalyst. This first gaseous mixture contains H 0 and HCl in amounts selected to result in a mole ratio of H 0 to HCl of about 20:1 to about 100: l; in addition, the amount of 0 contained therein is about 0.2 to about 3 mole percent thereof. After carbon is substantially removed from the catalyst, it is subjected to a treatment step involving contacting it with a second gaseous mixture for a period of about 0.5 to about hours at a relatively high temperature of about 450 to about 550 C. Like the first mixture, this second mixture contains H 0 and HCl in a mole ratio of 20:1 to about 100:1; in addition,.it contains about 0.2 to 25 mole percent 0 with an amount of about 1 to about 5 mole percent being preferred. Following this oxygen treatment step, oxygen is purged from contact with the catalyst with an inert gas stream. Thereafter, the catalyst is subjected to contact with a substantially sulfur-free third gaseous mixture comprising hydrogen, H 0 and HCl at a temperature of about 300 to about 600 C. for a final period of about 0.5 to about 5 hours. This third gaseous mixture contains H 0 and HCl in amounts sufficient to result in a mole ratio of H 0 to HCl of about 20:1 to about 50011. The regenerated catalyst recovered from this last step has activity, selectivity, and stability characteristics equivalent to those possessed initially by the fresh catalyst.

Some of the advantages associated with this method of catalyst regeneration are: (1) it does not require a high concentration of oxygen in the gas stream used during the oxygen treatment step although high concentrations can be used if desired. (2) since all major steps are performed in the presence of water, expensive dryer and/ or elaborate drying procedures are not necessary; (3) fairly low temperatures can be utilized in the reduction step; (4) the presence of chloride in the gas streams utilized in all major steps insures the automatic adjustment of the halogen component of the catalyst to the proper level; and (5) the positive requirements for exclusion of sulfur from the gas streams utilized in each of these steps, coupled with the initial sulfur-stripping step in the case of the sulfur-containing catalyst, eliminates the possibility of damaging the catalyst due to exposure to sulfur or sulfur oxides.

In another embodiment, the present invention is a regeneration method as summarized above in the embodiment first described above wherein the oxygen treating step comprises the substeps of: (1) treating the catalyst resutling from the carbon-burning step with the first gaseous mixture for about 0.5 to about 5 hours at a temperature of about 450 to about 550 C.; and thereafter, (2) increasing the amount of 0 contained in the first gaseous mixture by a factor of about 1.5 to about 8 and continuing the treating with thismodified mixture for an additional period of about 0.5 to about 5 hours at the same temperature.

Yet another embodiment relates to the embodiment of the regeneration method first described above wherein the mole ratios of H 0 to HCl utilized in the carbonburning step, the oxygen treatment step and the reduction step are selected from the range of about 50:1 to about :1 and wherein the amount of oxygen contained in the first gaseous mixture is about 0.5 to about 1.5 mole percent thereof.

Other objects and embodiments of the present invention encompass further details about the catalysts that can be regenerated thereby, the conditions and reagents used in each step of the regeneration method, and the mechanics associated with each of these steps. These embodiments and objects are hereinafter disclosed in the following detailed description of each of the essential and preferred steps of the present method.

As indicated above, the catalyst that is regenerated by the method of the present invention comprises a porous carrier material or support having combined therewith a platinum group component, a germanium component, and a halogen component. In many cases, it also contains a sulfur component. Considering first the porous carrier material, it is preferred that the material be a porous, adsorptive, high-surface area support having a surface area of about 25 to about 500 m. gm. The porous carrier material should be relatively refractory to the conditions utilized in the hydrocarbon conversion process; suitable carrier materials are: (l) activated carbon, coke, or charcoal; (2) silica or silica gel, clays and silicates including those synthetically prepared and naturally occurring, which may or may not be acid treated, for example, Attapulgus clay, china clay, diatomaceous earth, fullers earth, kaolin, kieselguhr, pumice, etc.; (3) ceramics, porcelain, crushed firebrick, and bauxite; (4) refractory inorganic oxides such as alumina, titanium dioxide, zirconium dioxide, chromium oxide, zinc oxide, magnesia, thoria, boria, silica-alumina, silica-magnesia, chromia-alumina, alumina-boria, silica-zirconia, etc.; (5) crystalline aluminosilicates such as naturally occurring or synthetically prepared mordenite and/ or faujasite, either in the hydrogen form or in a form which has been treated with multivalent cations; and, (6) combinations of one or more elements from these groups. The preferred porous carrier materials are refractory inorganic oxides, with best results obtained with an alumina carrier material. Suitable alumina materials are the crystalline aluminas known as the gamma-, eta-, and theta-alumina, with gamma or etaalumina giving best results. In addition, in some embodiments the alumina carrier material may contain minor proportions of other well known refractory inorganic oxides such as silica, zirconia, magnesia, etc.; however, the preferred carrier material is substantially pure gamma or eta-alumina. Preferred carrier materials have an apparent bulk density of about 0.30 to about 0.70 gm./cc. and surface area characteristics such that the average pore diameter is about 20 to 300 angstroms, the pore volume is about 0.10 to about 1.0 ml./gm. and the surface area is about to about 500 m. gm. In general, best results are typically obtained with a gamma-alumina carrier ma terial which is used in the form of spherical particles having: a relatively small diameter (i.e., typically about ,4 inch). an apparent bulk density of about 0.5 gm./cc. a pore volume of about 0.4 ml./ gm. and a surface area of about m. gm.

One essential constituent of the catalyst regenerated by the method of the present invention is a germanium component, and it is essential that the germanium component is present in the composite in an oxidation state above that of the elemental meal. That is to say, the germanium component will exist in the catalytic composite in either the +2 or +4 oxidation state with the latter being the most likely state. Accordingly, the germanium component will be present in the composite as a chemical compound, such as the oxide, sulfide, halide, etc., wherein the germanium is in the required oxidation state, or as a chemical combination with the carrier material in which combination the germanium exists in the higher oxidation state. On the basis of the evidence currently available, it is believed that the germanium component in the subject composite exists as germanous or germanic oxide. It is important to note that this limitation on the state of the germanium component requires extreme care in the preparation and use of the subject composite in order to insure that it is not subjected to high temperature reduction conditions effective to produce the germanium metal. This germanium component may be incorporated in the catalytic composite in any suitable manner known to the art such as by coprecipitation or cogelation with the porous carrier material, ion exchange with the gelled carrier material or impregnation with the carrier material either after or before it is dried and calcined. A preferred method of incorporating the germanium component into the catalytic composite involves utilization of a soluble, decomposable compound of germanium to impregnate the porous carrier material. In general, the solvent used in this impregnation step is selected on the basis of the capability to dissolve the desired germanium compound and is preferably an aqueous, acidic solution. Thus, the germanium component may be added to the carrier material by commingling the latter with an aqueous, acidic solution of suitable germanium salt or suitable compound of germanium such as germanium tetrachloride, germanium difluoride, germanium tetrafluoride, germanium di-iodide, germanium monosulfide, and the like compounds. A particularly preferred impregnation solution comprises germanium metal dissolved in chlorine water. In general, the germanium component can be impregnated either pror to, simultaneously with, or after the platinum group component is added to the carrier material. However, excellent results are obtained when the germanium component is impregnated simultaneously with the platinum group component. In fact, a preferred impregnation solution contains chloroplatinic acid, hydrogen chloride, and germanium metal dissolved in chlorine water.

As indicated above, the catalyst to which the regeneration method of the present invention is applicable also contains a platinum group component. Although the method of the present invention is specifically directed to the regeneration of a catalytic composite containing latinum, it is intended to include other platinum group metals such as palladium, rhodium, ruthenium, osmium, and iridium. The platinum group component, such as platinum, may exist within the final catalytic composite as a compound such as an oxide, sulfide, halide, etc., or as an elemental metal. Generally, the amount of the platinum group component present in the final catalyst composite is small compared to the quantities of the other components combined therewith. In fact, the platinum group component generally comprises about 0.01 to about 2 wt. percent of the final catalytic composite, calculated on an elemental and carbon-free basis. Excellent results are obtained when the catalyst contains about 0.05 to about 1 wt. percent of the platinum group metal. The preferred platinum group component is platinum or a compound of platinum. The platinum group component may be incorporated in the catalytic composite in any suitable manner such as coprecipitation or cogelation with the preferred carrier material, or ion exchange or impregnation thereof. The preferred method of preparing the catalyst involves 8 the utilization of a water-soluble, decomposable compound of a platinum group metal to impregnate the carrier material. Thus, the platinum group component may be added to the support by commingling the latter with an aqueous solution of chloroplatinic acid.

Another essential constituent of the catalyst regenerated by the instant method is the halogen component. Although the precise form of the chemistry of the association of the halogen component with the carrier material is not entirely known, it is customary in the art to refer to the halogen component as being combined with the carrier material or with the other ingredients of the catalyst. This combined halogen may be either, fluorine, chlorine, iodine, bromine, or mixtures thereof. Of these, fluorine and, particularly, chlorine are preferred. The halogen may be added to the carrier material in any suitable manner either during preparation of the carrier material or before or :after the addition of the other components. For example, the halogen may be added at any stage of the preparation of the carrier material or to the calcined carrier material as an aqueous solution of an acid such as hydrogen fluoride, hydrogen chloride, hydrogen bromide, etc. For reforming, the halogen is combined with the carrier material in an amount suflicient to result in a final composite that contains about 0.5 to about 3.5 wt. percent and preferably about 0.6 to about 1.2 by weight of the halogen calculated on an elemental and carbon-free basis. In isomerization or hydrocracking embodiments, it is generally preferred to utilize relatively larger amounts of halogen in the catalyst-typically ranging up to about 10 wt. percent calculated on an elemental and carbon-free basis, and more preferably about 1 to about 5 wt. percent. In a reforming embodiment, the preferred halogen component is chlorine or a compound thereof.

Relative to the amount of the germanium component contained in the composite regenerated by the instant method, it is preferably suflicient to constitute about 0.01 to about 5 wt. percent of the final composite, calculated on an elemental and carbon-free basis, although substan tially higher amounts of germanium may be utilized in some cases. In a reforming embodiment best results are typically obtained with about 0.05 to about 2 wt. percent germanium. In the case where the germanium component is incorporated in the catalyst by coprecipitating it with the preferred alumina carrier material, it is within the scope of the present invention to prepare composites containing up to 30 wt. percent germanium, calculated on an elemental basis. Regardless of the absolute amounts of the germanium component and the platinum group component utilized, the atomic ratio of germanium to the platinum group metal contained in the catalyst is preferably selected from the range of about 0.1:1 to about 10:1, with best results achieved at an atomic ratio of about 1:1 to 6:1. This is particularly true when the total content of the germanium component plus the platinum group component in the catalytic composite is fixed in the range of about 0.1 to about 3.0 wt. percent thereof, calculated on an elemental germanium and platinum group metal basis.

Regardless of the details of how the components of this catalyst are combined with the porous carrier material, the final catalyst generally will be dried at a temperature of about 200 to about 600 F. for a period of from about 2 to about 24 hours or more, and finally calcined at a temperature of about 700 F. to about 1100 F. in an air atmosphere for a period of about 0.5 to about 10 hours in order to convert the metallic components substantially to the oxide form.

It is preferred that the resultant calcined catalytic composite be subjected to a substantially water-free reduction step prior to its use in the conversion of hydrocarbons. This step is designed to insure a uniform and finely divided dispersion of the metallic component throughout the carrier material. Preferably, substantially pure and dry hydrogen (i.e., less than 20 vol. ppm. H O) is used .9 as the reducing agent in this step. The reducing agent is contacted with the calcined catalyst at conditions including a temperature of about 800 F. to about 1000" F. selected to reduce the platinum group component to the metallic'state while maintaining the germanium component in an oxidized state.

The resulting reduced catalytic composite may, in some cases, be beneficially subjected to a presulfiding step designed to incorporate in the catalytic composite from about 0.05 to about 0.50 wt. percent sulfur calculated on an elemental basis. Preferably, this presulfiding treatment takes place in the presence of hydrogen and a suitable sulfur-containing compound such as hydrogen sulfide, lower molecular weight mercaptans, organic sulfides etc.

As indicated above, in some embodiments of the present invention, the catalyst that is regenerated thereby will contain a sulfur component. Typically the major portion of this sulfur carrier from sulfur or sulfur-containing compounds which are present in the charge stock or from the deliberate injection of sulfur into the hydrocarbon conversion process or from inadvertent upsets off upstream treating facilities or from any of the other sources Well known to those skilled in this art. Regardless of the source, it is within the scope of the instant method to regenerate catalysts containing about 0.01 to about wt. percent or more sulfur, with this amount being more commonly about 0.05 to about 1 wt. percent.

In one preferred embodiment, the catalyst regenerated by the present invention is a combination of a platinum component, a chlorine component, a germanium component, and a sulfur component with an alumina carrier material. These components are typically present in amounts sufiicient to result in the catalyst containing, on an elemental and carbon-free basis, about 0.6 to about 1.2 wt. percent chlorine, about 0.05 to about 1 wt. percent platinum, about 0.05 to about 2 wt. percent germanium and about 0.05 to about 1 wt. percent sulfur.

As indicated hereinbefore, the principal utility for the subject catalyst is in a hydrocarbon conversion process wherein a dual-function hydrocarbon conversion catalyst having a hydrogenation-dehydrogenation function and an acid-acting function has been traditionally used; for example, these catalysts are used in a reforming process with excellent results. In a typical reforming process, a hydrocarbon charge stock boiling in the gasoline range and hydrogen are contacted with the catalyst of the type described above in a conversion zone at reforming conditions. The hydrocarbon charge stock will typically comprise hydrocarbon fractions containing naphthenes and paraffins that boil within the gasoline range. The preferred class of charge stocks includes straight run gasolines, natural gasolines, synthetic gasoline, etc. The gasoline charge stock may be a full boiling range gasoline having an initial boiling point of about 50- to about 150 F., and an end boiling point within the range of about 250 to 425 F., or it may be a selective fraction thereof which generally will be a higher boiling fraction commonly referred to as a heavy naphtha-for example, a naphtha boiling in the range of C to 400 F. provides an excellent charge stock. In general, the conditions used in the reforming process are: a pressure of about 50 to about 1000 p.s.i.g. with the preferred pressure being 100 to about 600 p.s.i.g., a temperature of about 800 to about 1100 F. and preferably about 900 to about 1050 F., a hydrogen to hydrocarbon mole ratio of about 2 to about 20 moles of H per mole of hydrocarbon and preferably about 4 to about 10 moles of H per mole of hydrocarbon, and a liquid hourly space velocity (which is defined as the equivalent liquid volume flow rate per hour of the hydrocarbon charge stock divided by the volume of the bed of catalyst particles) of about 0.1 to about 10 hrr with a value in the range of about 1 to about 3 hr.- giving best results.

When the catalysts of the type described above are employed in the conversion of hydrocarbons, particularly the reforming process outlined above, the activity, selectivity, and stability of these catalysts are initially quite acceptable. For example, in a reforming process this type of catalyst has several singular advantages, among which are increased C yield, decreased rate of coke laydown on the catalyst, increased hydrogen make, enhanced stability of both C yield and temperature necessary to make octane, and excellent catalyst life before regeneration becomes necessary. However, the gradual accumulation of coke and other deactivating carbonaceous deposits on the catalyst will eventually reduce the activity and selectivity of the process to a level such that regeneration is desirable. Ordinarily, regeneration becomes desirable when about /2 to about 25 percent by weight of carbonaceous deposits have been formed upon the catalyst.

When the performance of the catalyst has decayed to the point where it is desired to regenerate the catalyst, the introduction of the hydrocarbon charge stock into the conversion zone containing the catalyst is typically stopped. Thereafter, the regeneration method of the present invention is performed either in situ or the catalyst may be unloaded from the conversion zone and regenerated in an off-line facility. It is to be noted that the scope of the method of the present invention includes two distinct modes of operation depending on whether or not the deactivated catalyst contains labile sulfur. If it does, it is essential that a sulfur-stripping step be performed before any of the coke is removed from the deactivated catalyst. On the other hand, if it does not, this sulfur-stripping step may be omitted. In either case, it is an essential feature of the subject regeneration method that the composition of the gas streams used in the various steps thereof are carefully controlled. In particular, it is a critical feature of the present invention that the gas streams used during the sulfur-stripping step, the carbonburning step, the oxygen-treating step, and the reduction step are substantially free of compounds of sulfurpar ticularly, oxides of sulfur and H 8. It is, therefore, evident that the gas streams used in each of the steps of the present invention may be once-through streams or recycle streams; provided that in this latter case, the recycle streams are treated by conventional techniques to insure the absence of detrimental constituents therefrom. Furthermore, it is to be noted that the temperatures given hereinafter for each of the steps refer to the temperature of the gas stream used therein just before it contacts the catalyst, and that the composition of the gas streams utilized are given in mole percent which are, of course, substantially the same as when expressed in volume percent.

When the deactivated catalyst contains labile sulfur, the first step of the regeneration method involves subjecting the deactivated catalyst to contact with a substantially sulfur-free hydrogen stream at conditions selected to strip labile sulfur from the catalyst and associated hardware of the hydrocarbon conversion plant. Labile sulfur is used here to mean the sulfur contained in the catalyst that can be removed by hydrogen stripping. This hydrogen stream preferably contains H 0 and HCl in amounts, respectively, sutficient to result in a mole ratio of H 0 to HCl of about 20:1 to about 100:1, with best results ordinarily obtained at a mole ratio of about 50:1 to about 1. In general, when the hydrogen stream contains H 0 and HCl it is preferred to operate with a relatively minor amount of water in this hydrogen stream, with best results obtained when the amount of water contained therein is suflicient to comprise about 0.5 to about 2 mole percent thereof, although in some cases higher amounts of 'Water may be utilized if the restriction given above with respect to mole ratio is observed. Accordingly, in a preferred mole of operation, this hydrogen stream consists essentially of a hydrogen stream containing about 0.5 to about 2 mole percent Water and about 0.005 to about 0.1 mole percent HCl. It is to be noted, both here and in the subsequent steps, that when reference is made to HCl being contained in the gas streams, it is intended to include both the situation where HCl per se is added to the gas streams and where a chloride-containing compound, which is convertible to hydrogen chloride under the conditions utilized in these steps, is added to these gas stream. Examples of these last compounds are chlorine, alkyl chlorides, carbon tetrachloride and the like compounds.

This sulfur-stripping step is preferably conducted at a relatively high temperature of about 350 to about 600 C., with best results obtained at about 400 to 550 C. Similarly, the pressure utilized is preferably about 1 to about 50 atmospheres, with best results obtained when a relatively high pressure is utilized in conjunction with a relatively high temperature. Likewise, the gas hourly space velocity can be selected from a relatively broad range of about 100 to 25,000 hr. This sulfur-stripping step is performed for a period extending until the resulting effluent gas stream is substantially free of hydrogen sulfide: that is, less than about 10 vol. p.p.m. and preferably less than 1 vol. p.p.m. The hydrogen stream utilized in this step can be a once-through stream or a recycle stream, provided, in the latter case, that suitable arrangements are made to scrub H S from the recirculated gas stream. An acceptable scrubbing procedure, both here and in subsequent steps, involves, for example, contacting the effiuent gas stream withdrawn from the zone containing the deactivated catalyst with a strong basic solution such as an aqueous solution of an alkali metal or alkaline earth salt of a weak acid. A preferred scrubbing procedure involves scrubbing with a solution of sodium hydroxide or sodium carbonate which is maintained at a pH of about 7 to 11. In a commercial hydrocarbon conversion plant, this scrubbing operation can easily be performed by circulating a basic solution from the hydrogen separator to the inlet to the reactor effluent cooling means with suitable addition of fresh solution and withdrawal of spent solution to maintain the desired pH level.

This labile sulfur-stripping step is to be sharply distinguished from the conventional volatile hydrocarbonstripping step which is ordinarily performed during the shutdown procedure when the catalyst has deactivated and is taken off stream. It is customary for platinum metal containing catalysts to perform this volatile hydrocarbonstripping step with a hydrogen-containing stream; however, the function of this last stripping step is to remove volatile hydrocarbons and it is terminated when the efiluent gas stream becomes free of same. Thus, this conventional stripping step ordinarily is completed in about .5 to about 2 hours. In sharp contrast, the sulfur-stripping step required by the present invention lasts until the efilu ent gas stream is substantially free of hydrogen sulfide, which is ordinarily a much longer period of about to 30 or more hours, depending upon the exact stripping conditions utilized and the amount of labile sulfur initially on the catalyst.

Although it is not particularly preferred, an alternative mode of operation of this sulfur-stripping step involves contacting a substantially sulfur-free mixture of hydrogen and charge stock with the sulfur-containing catalyst at conditions selected to convert hydrocarbons and to strip labile sulfur. This contacting is usually performed with recycle gas scrubbing, as explained hereinbefore, for a period of time extending until the efiluent stream from this contacting step is substantially free of hydrogen sulfide; that is, less than about 10 vol. p.p.m. and preferably less than 1 vol. p.p.m.

It is to be understood that, if the catalyst is regenerated in situ in a plant that has been exposed to sulfur, it is generally a preferred practice to burn sulfide scale from the plant hardware prior to this sulfur-stripping step. ln

particular, the sulfide scale should be at least removed from the charge heater as this is the point of maximum accumulation of sulfur when it is introduced in the charge stock. This sulfide scale burning step, at the minimum, should be conducted at a temperature and O concentration which are more severe than any subsequently encountered during the regeneration procedure.

Following this sulfur-stripping step, residual hydrogen is removed from contact with the resulting catalyst by purging with an inert gas such as nitrogen. A preferred mode of operation for this purging step involves use of an inert gas stream that contains H 0 and HCl in a mole ratio of about 20:1 to about 100:1.

After hydrogen is purged from contact with the labile sulfur-free catalyst, the next step involves burning carbon or coke from the resulting catalyst. This involves subjecting the deactivated catalyst to contact with a substantially sulfur-free first gaseous mixture containing oxygen, H 0, and HCl at carbon-burning conditions. Preferably, the amount of oxygen contained in this first gaseous mixture is maintained within the range of about 3 mole percent thereof, with best results obtained when it is about 0.5 to about 1.5 mole percent thereof. Similarly, it is necessary to maintain the mole ratio of H 0 to HCl contained in this first gaseous mixture within the range of about 20:1 to about 100:1, with best results obtained at a ratio of about 50:1 to about :1. In addition, the amount of water contained in this first gaseous mixture preferably comprises about 0.5 to about 2 mole percent thereof. The balance of the gaseous mixture is an inert gas such as nitrogen, helium, carbon dioxide, etc. The conditions utilized in this carbon-burning step are: a temperature of about 375 to about 450 C., a pressure sufficient to maintain the flow of this second gaseous'mixture through the zone containing the catalyst and preferably about 30 atmospheres, and a gas hourly space velocity (defined as the volume rate of flow of the gas stream per hour at standard conditions divided by the volume of the catalyst bed) of about to about 25,000 hrf This carbon-burning step is performed for a time period sufiicient to substantially remove carbonaceous materials from the catalyst. In general, depending obviously upon the amount of carbonaceous materials present on the catalyst, a carbon-burning period of about 5 to about 30 hours is adequate, with best results typically obtained in about 20 to about 30 hours. A convenient criterion for determining when this carbon-burning step is essentially complete involves monitoring the AT across the reactor containing the catalyst, when this parameter is less than about 5 C. then the carbon-burning step for this reactor can be considered finished. For a multi-reactor system, the beds of the catalyst are preferably regenerated in seriatim With the AT across the last reactor in series being the con trolling parameter.

The next essential step of the present regeneration method involves treating the catalyst resulting from the carbon-burning step with a substantially sulfur-free second gaseous mixture containing 0 H 0 and HCl for a period of about 0.5 to about 10 hours at a relatively high temperature. This second gaseous mixture contains 0 in an amount of about 0.2 to about 25 mole percent thereof with a value of about 1 to 5 being preferred. Likewise, it contains H 0 and HCl in a mole ratio of H 0 to HCI of about 20:1 to about 100:1, with best results obtained at a mole ratio of about 50:1 to about 90: 1. The temperature utilized in this second step is selected from the range of about 450 to about 550 C. The other conditions are preferably selected from the ranges previously given in the discussion of the carbon-burning step. A preferred mode of operation of this step involves conducting this treatment in two substeps: the first substep involving treating the catalyst resulting from the carbonburning step with the first gaseous mixture for a period of about 0.5 to about 5 hours at a temperature of about 450 to about 550 C. The second substep then involves increasing the amount of oxygen contained in the first gaseous mixture by a factor of about 1.5 to about 8 and thereafter continuing the treating with this second gaseous mixture for a period of about 0.5 to about 5 hours at the same temperature as utilized in the first substep. Another preferred mode of operation of this treatment step involves, in the first substep, increasing the amount of contained in the first gaseous mixture by a factor of about 1.5 to about 8, preferably about 2, to form the second gaseous mixture and treating the catalyst resulting from the carbon-burning step with this second gaseous mixture at a temperature of about 375 to about 450 C. for about 0.5 to about hours. Thereafter, in the second substep, the resulting catalyst is treated with this second gaseous mixture at a temperature of about 450 to about 550 C. for an additional period of about 0.5 to about 5 hours. The function of this oxygen treating step is to remove trace amounts of carbonaceous materials which were not burned off during the first step and to convert the metallic components of the catalyst (i.e., the platinum group and germanium components) to a highly oxidized state.

After this oxygen-treating step, oxygen is purged from contact with the resulting catalyst by means of a suitable inert gas stream. In view of the fact that the subsequent reduction step is conducted under a wet condition, it is not necessary to dry the plant during this step. All that is necessary is to displace oxygen from contact with the catalyst, and the period of time necessary to do this can easily be determined by monitoring the efliuent gas stream from the zone containing the catalyst.

Upon com letion of this last purge step, the final essential step of the regeneration method is commenced. It involves contacting the oxygen-treated catalyst with a substantially sulfur-free third gaseous mixture comprising hydrogen, H 0, and H01 at a temperature of about 300 to about 600 C., with best results obtained at a relatively low temperature of 325 to 425 C., for a final period of about 0.5 to about 5 hours. The amounts of H 0 and HCl in this third gaseous mixture are selected so that the mole ratio of H 0 to HCl is about 20:1 to about 500:1, and preferably about 20:1 to about 100:1, with best results obtained at about 50:1 to about 90:1. Similarly, the amount of H 0 contained in this third gaseous mixture is preferably about 0.5 to about 2 mole percent thereof. In many cases, it is beneficial to conduct this reduction step in two substeps: the first involving a relatively low partial pressure of H of about 0.5 to about 2 atmospheres, and the second involving a relatively high partial pressure of H of about 5 to about atmospheres. Once again, the pressure and gaseous flow rates utilized for this step are preferably identical to those given in conjunction with the discussion of the carbon burning step. The purpose of this reduction step is to reduce the platinum group component of the catalyst to the elemental state while holding the germanium component in an oxidized state, thereby producing a regenerated catalyst having activity, selectivity, and stability characteristics comparable to those possessed initially by the fresh catalyst.

Following this reduction step, the hydrocarbon conversion process in which the catalyst is utilized may be restarted by once again charging the hydrocarbon stream in the presence of hydrogen to the zone containing the regenerated catalyst at conversion conditions designed to produce the desired product. In the preferred case, this involves reestablishing reforming conditions within the zone containing the catalyst. In many cases, it is advantageous to dry the regenerated catalyst by stripping water therefrom at an elevated temperature before the process is restartedfor example, the regenerated catalyst can be contacted with a water-free hydrogen stream at 400 C. for about 1 hour.

14 The following example is given to illustrate further the regeneration method of the present invention and to indicate the benefits that are gained by the utilization thereof. It is understood that the example is given for the sole purpose of illustration.

EXAMPLE This example demonstrates the regeneration method of the present invention by contrasting the results obtained in an accelerated reforming stability test with the fresh caalyst and with the regenerated catalyst.

An alumina carrier material comprising A inch spheres was prepared by: forming an aluminum hydroxyl chloride sol by dissolving substantially pure aluminum pellets in a hydrochloric acid solution, adding hexamethylenetetramine to the resulting sol, gelling the resulting solution by dropping it into an oil bath to form spherical particles of alumina hydrogel. The resulting hydrogel particles were then aged and washed with an ammoniacal solution and finally dried and calcined at an elevated temperature to form spherical particles of gamma-alumina containing about 0.3 Wt. percent combined chloride. Additional details as to this method of preparing the preferred carrier material are given in the teachings of US. Patent No. 2,620,314.

A measured amount of germanium dioxide crystal was placed in a porcleain boat and subjected to a reduction treatment with substantially pure hydrogen at a temperature of about 650 C. for about 2 hours. The resulting grayish-black solid material was then dissolved in chlorine water to form first aqueous solution. A second aqueous solution containing chloroplatinic acid and hydrogen chloride was then prepared. The two solutions were then intimately admixed and used to impregnate the gammaalumina particles in amounts, respectively, calculated to result in a final composite containing 0.25 wt. percent Ge and 0.375 wt. percent Pt. In order to insure uniform distribution of both metallic components throughout the carrier material, this impregnation step was performed by adding the carrier material particles to the impregnation mixture with constant agitation. In addition, the volume of the solution was two times the volume of the carrier material particles. The impregnation mixture was maintained in contact with the carrier material particles for a period of about /2 hour at a temperature of about 70 F. Thereafter, the temperature of the impregnation mixture was raised to about 225 F. and the excess solution was evaporated in a period of about 1 hour. The resulting dried particles were then subjected to a calcination treatment in an air atmosphere at a temperature of about 925 F. for about 1 hour. The calcined spheres were then contacted with an air stream containing H 0 and HCl in a mole ratio of about 40:1 for about 4 hour at 975 F. in order to adjust the halogen content of the catalyst particles to a value of about 0.90.

The resulting catalyst particles were analyzed and found to contain, on an elemental basis, about 0.375 wt. percent platinum, about 0.25 wt. percent germanium, and about 0.85 wt. percent chloride.

Thereafter, the catalyst particles were subjected to a dry pre-reduction treatment by contacting them with a substantially pure hydrogen stream containing less than 20 vol. p.p.m. H O at a temperature of about 1000 F., a pressure slightly above atmospheric and a flow rate of the hydrogen stream through the catalyst particles corresponding to a gas hourly space velocity of about 720 hr. This pre-reduction step was for a duration of about 1 hour.

An analysis of the fresh catalyst is given in Table I and its composition reported on a weight percent of element basis. Also shown in Table I is an analysis of the deactivated catalyst. The deactivated catalyst had been used in a sulfur-free reforming operation in which extraordinary measures were taken to exclude sulfur therefrom; conse- 15 quently it contained essentially no labile sulfur and a preliminary sulfur-stripping step was not required.

TABLE I.COMPOSITION OF CATALYSTS Pt wt. G wt. Cl wt. S wt. C wt. Catalysts percent percent percent percent percent Fresh 375 0. 25 0. 85 0. 1 0 Deactivated l 0. 375 l 0. 25 1 0.85 0. 1 6. 26 Regenerated 0. 375 0. 25 1. 02 0. 1 0. 1

1 Based on carbon-free catalyst.

The reforming stability test consisted of six periods of 24 hours with a 12 hour line-out period being followed by a 12 hour test period. The conditions utilized in the tests were as follows: a pressure of 100 p.s.i.g., a mole ratio of hydrogen to hydrocarbon of 9:1, a LHSV of 1.5 hr. and a temperature which is continuously adjusted to achieve a target octane of 102 F-l clear for the C reformate.

The results of these comparison tests are given in Table IV in terms of temperatures necessary during each period to achieve target octane, the excess recycle gas recovered from the hydrogen separator in standard cubic feet per barrel of charge (s.c.f.b.), the debutanizer overhead gas in s.c.f.b., the ratio of debutanizer gas to total gas make, the C yield on a vol. percent of charge basis, and the CH make in s.c.f.b.

TABLE III-SUMMARY OF REGENERATION METHOD Mole tep Temp. G.h.s.v. Pressure Time ratio, No. Composition of bar stream, mole percent C: hr.,i p.s.1.gi hr. HzO/HCI 1 0.01 E01 0.71 H O 1.0 O andN 400 750 5 22 72:1 2 2 2 500 750 5 1 721 The regenerated catalyst was then subjected to a high stress reforming stability test, and the results obtained compared with a similar test performed on the corresponding fresh catalyst.

The stability tests were performed in a laboratory scale reforming plant comprising a reactor containing a fixed bed of the catalyst, a hydrogen separator, a high surface area sodium dryer, a debutanizer column, and other conventional equipment such as pumps, compressors, heating and cooling means, etc. the details of Which are well known to those skilled in the reforming art.

The flow scheme utilized in this laboratory scale reforming plant is as follows: (1) the charge stock and hydrogen are commingled, heated to conversion temperature and passed into the reactor; (2) an efiiuent stream is withdrawn from the reactor, cooled to about 55 F, and passed to the hydrogen separator wherein a hydrogen-rich gas separates from a hydrocarbon liquid phase; (3) the hydrogen-rich gas phase is withdrawn and a portion of it vented from the system in order to maintain pressure control; another portion is passed through the high surface area sodium dryer, recompressed and ultimately recycled to the reactor; and (4) the liquid phase from the separator is passed to the debutanizer column wherein light ends are taken overhead and a C reformate recovered as bottoms.

The characteristics of the charge stock used in the accelerated stability test are given in Table 111.

TABLE IIIANALYSIS OF HEAVY KUWAIT NAPHTHA AP'I gravity at 60 F. 60.4 Initial boiling point, F 184 10% boiling point, F. 205 50% boiling point, F. 256 90% boiling point, F. 321 End boiling point, F. 360 Sulfur, wt. p.p.m. 0.5 Nitrogen, wt. p.p.m. 0.1 Aromatics, vol. percent 8 Parafiins, vol. percent 71 Naphthenes, vol. percent 21 Water, p.p.m. 5.9

Octane uo., F-l clear 40.0

TABLE VI.COMPARISON OF FRESH AND REGENERATED CATALYSTS IN ACCELERA'IED REFORMING STABILITY TEST Period Number Temp., F;

Fresh 962 973 979 986 990 904 Regenerated 966 972 977 981 988 993 ERG,s.c.f.b.: H

Fresh 1, 733 1, 700 1, 790 1, 788 1, 767 1, 713

Regenerated 1, 788 1, 775 1, 796 1, 794 1, 772 1, 792 DOH s.c.f.b.:

Fi esh 00 e5 00 as as as Regeuerated... L. 35 65 62 70 63 63 DOH total as ma e:

Fl eslL M .033 .037 .036 .034 .037 .037

Rcgenerated 019 035 033 038 034 034 0 vol. percent:

Fresh 77. 6 77. 0 77. 2 77. 6 76. 4 17.0

Regent-Hated. 78. 5 78. 8 77. 7 76. 6 78. 0 77. 0 CH s.c.f.b.:

Iresh 77 78 77 83 81 Regenerated 74 67 67 70 65 70 As previously explained, the temperature required to make octane, at constant conditions for the same charge stock is a good measure of activity of the catalyst. On this basis, it can be determined from Table IV that the regenerated catalyst required a temperature to make octane which was approximately the same as the corresponding fresh catalystthis indicates that the regenerated catalyst was as active as the fresh catalyst.

Similarly, (3 yield at octane is a precise indicator of catalyst selectivity for reforming reactions, and by comparing the C,-,-{- yield data given in Table IV for the fresh catalyst with that for the regenerated catalyst, it is manifest that the regenerated catalyst has selectivity characteristics which are equivalent to the fresh catalyst.

Insofar as stability is concerned, the rate of change with time of temperature necessary to make octane and of C yield are commonly used to measure this performance characteristic. From Table IV it can be ascertained that the stability characteristics for the fresh catalyst and the regenerated catalyst are comparable.

Accordingly, it is clear from the comparative data presented in Table IV that the regeneration method of the present invention resulted in a regenerated catalyst possessing activity, stability, and selectivity characteristic! that are equivalent or better than those possessed by the 17 fresh catalyst. It is intended to cover all changes and modifications of the above disclosure of the present invention which would be self-evident to a man of ordinary skill in the catalyst regeneration art.

I claim as my invention:

1. A method for regenerating a deactivated hydrocarbon conversion catalyst comprising a labile sulfur-free combination of catalytically effective amounts of a platinum group component, a germanium component present in an oxidation state above that of the elemental metal and a halogen component with a refractory inorganic oxide carrier material, the catalyst having been deactivated by the deposition of carbonaceous materials thereon during a previous contacting with a hydrocarbon charge stock at hydrocarbon conversion conditions, said method comprising the sequential steps of:

(a) contacting the deactivated catalyst with a substantially sulfur-free first gaseous mixture containing H 0 and HClthe amount of 0 being about 0.2 to about 3 mole percent thereof and the mole ratio of H 0 to HCl contained therein being selected from the range of about 20:1 to about 100:lat a temperature of about 375 to about 450 C. for a period sufficient to substantially remove said carbonaceous materials;

(b) treating the catalyst resulting from step (a) by contacting it with a substantially sulfur-free second gaseous mixture containing 0 H 0 and HCl-the amount of 0 being about 0.2 to about 25 mole percent thereof and the mole ratio of H 0 to HCl contained therein being selected from the range of about 20:1 to about 100:1at a temperature of about 450 to about 550 C. for a period of about 0.5 to about hours;

(c) purging oxygen from contact with the catalyst from step (b); and,

(d) subjecting the catalyst resulting from step (c) to contact with a substantially sulfur-free third gaseous mixture comprising hydrogen, H 0 and HCl-- the mole ratio of H 0 to HCl being selected from the range of from about :1 to about 500:1--at a temperature of about 300 to 600 C. for a final period of about 0.5 to about 5 hours, thereby producing a regenerated hydrocarbon conversion catalyst having activity, selectivity, and stability characteristics comparable to those possessed initially by the fresh catalyst.

2. A method as defined in claim 1 wherein the platinum group component of the catalyst is platinum or a compound of platinum.

3. A method as defined in claim 1 wherein the halogen component of the catalyst is chlorine or a compound of chlorine.

4. A method as defined in claim 1 wherein said refractory inorganic oxide is alumina.

5. A method as defined in claim 1 wherein said catalyst contains, on an elemental and carbon-free basis,

about 0.01 to about 3 wt. percent of the platinum group metal, about 0.01 to about 5 Wt. percent of germanium and about 0.5 to about 3.5 wt. percent halogen.

6. A method as defined in claim 1 wherein the mole ratios of H 0 to HCl utilized in steps (a) (b) and (d) are selected from the range of about 50:1 to about 90:1.

7. A method as defined in claim 1 wherein the temperature utilized in step (d) is about 325 about 425 C.

8. A method as defined in claim 1 wherein step (b) comprises the substeps of:

(1) treating the catalyst resulting from step (a) with said first gaseous mixture for about 0.5 to about 5 hours at a temperature of about 450 to about 550 C.; and, thereafter,

(2) increasing the amount of 0 contained in said first gaseous mixture by a factor of about 1.5 to about 8 and continuing the treating for an additional 18 period of about 0.5 to about 5 hours at the same temperature as utilized in substep (l) 9. A method of defined in claim 1 wherein step (b) comprises the substeps of:

(1) increasing the amount of 0 contained in the first gaseous mixture by a factor of about 1.5 to about 8 to form the second gaseous mixture and treating the catalyst resulting from step (a) with this second gaseous mixture at a temperature of about 375 to about 450 C. for about 0.5 to about 5 hours; and, thereafter,

(2) treating the resulting catalyst with the second gaseous mixture at a temperature of about 450 to about 550 C. for an additional period of about 0.5 to about 5 hours.

10. A method as defined in claim 1 wherein the amount of oxygen contained in the first gaseous mixture is about 0.5 to about 1.5 mole percent.

11. A method as defined in claim I wherein the amount of oxygen contained in the second gaseous mixture is about 1 to about 5 mole percent.

12. A method as defined in claim 1 wherein the period utilized in step (a) extends until the AT across the catalyst bed is less than 5 C.

13. A method for regenerating a deactivated hydrocarbon conversion catalyst comprising a combination of catalytically effective amounts of a platinum group component, a germanium component present in an oxidation state above that of the elemental metal, a halogen component and a sulfur component with a refractory inorganic oxide carrier material, the catalyst having been deactivated by the deposition of carbonaceous materials during a previous contacting with a hydrocarbon charge stock at hydrocarbon conversion conditions, said method comprising the sequential steps of:

(a) contacting the deactivated catalyst with a substantially sulfur-free hydrogen stream at a temperature of about 350 to about 600 C. for a period extending until the resulting eflluent gas stream is substantially free of hydrogen sulfide;

(b) purging hydrogen from contact with the catalyst resulting from step (a); and thereafter;

(0) subjecting the catalyst resulting from step (b) to contact with a substantially sulfur-free first gaseous mixture containing 0 H 0 and HCl-the amount of 0 being about 0.2 to about 3 mole percent thereof and the mole ratio of H 0 to HCl contained therein being selected from the range of about 20:1 to about :1-at a temperature of about 375 to about 450 C. for a period sufiicient to substantially remove said carbonaceous materials;

(d) treating the catalyst resultin from step (c) by contacting it with a substantialy sulfur-free second gaseous mixture containing 0 H 0 and HCl-the amount of 0 being about 0.2 to about 25 mole percent thereof and the mole ratio of H 0 to HCl contained therein being selected from the range of about 20:1 to about 100:1-at a temperature of about 450 to about 550 C. for a period of about 0.5 to about 10 hours;

(e) purging oxygen from contact with the catalyst from step (d); and,

(f) subjecting the catalyst resulting from step (e) to contact with a substantially sulfur-free third gaseous mixture comprising hydrogen, H 0 and HCl--the mole ratio of H 0 to HCl being selected from the range of from about 20:1 to about 500:1--at a temperature of about 300 to 600 C. for a final period of about 0.5 to about 5 hours, thereby producing a regenerated hydrocarbon conversion catalyst having activity, selectivity, and stability characteristics comparable to those possessed initially by the fresh catalyst.

19 20 14. A method as defined in claim 13 wherein the period 2,906,701 9/1959 Stine et a1 208138 utilized in step (21) extends until the resulting efliuent 3,481,861 12/ 1969 Hayes 208--140 gas stream contains less than 1 vol. p.p.m. of H 8. 3,496,096 2/1970 Kluksdahl 252419 15. A method as defined in claim 13 wherein the hydro- 3,567,656 3/ 1971 Mitsche 252466 gen stream utilized in step (21) contains H and HCl 5 in a mole ratio of H 0 to HCl of about :1 to about DANIEL E. WYMAN, Primary Examiner :1 P. E. KONOPKA, Assistant Examiner References Cited UNITED STATES PATENTS 10 US. Cl. X.R. 2,785,139 3/1957 Heinernann 252415 208; 252419 2,906,700 9/1959 Stine et a1. 208-138 

